Fixing MHonarc for mime-type application/vnd.ms-excel

All,
I ran into a problem with MHonarc v. 1.2.3 processing an application type of
"application/vnd.ms-excel". After some investigation, I theorized that the
problem lay in the fact that we're pattern matching against "[\w-/]+" for the
content-type, meaning that the period (and anything after it) is not part of
the content-type, resulting in a non-match.
MHonarc appears to do content-type pattern matching in mhonarc, mhexternal.pl
and readmail.pl. I've altered the pattern match for content-type in these
files to be "[\w-/\.]+"; this seems to have fixed the problem.
For example, in the mhonarc file, the original line:
($tmp = $fields{'content-type'}) =~ m%^\s*([\w-/]+)%;
becomes...
($tmp = $fields{'content-type'}) =~ m%^\s*([\w-/\.]+)%;
Does anyone think that I've broken something by making these modifications?
Regards,
Will
P.S. Please respond directly as I am not on this mailing list.